The present invention relates generally to systems for the aseptic packaging of food products. More particularly, the present invention relates to an apparatus and method for providing container interior sterilization in an aseptic processing apparatus.
Sterilized packaging systems in which a sterile food product is placed and sealed in a container to preserve the product for later use are well known in the art. Methods of sterilizing incoming containers, filling the containers with pasteurized product, and sealing the containers in an aseptic sterilization tunnel are also known.
Generally, containers such as cups are sterilized using a mixture of hydrogen peroxide and a carrier gas such as air. The hydrogen peroxide vapor mixture is directed against the interior surface of the cup and a condensate film forms. Cups typically have a ratio of an opening diameter to a height of greater than 1.0. The hydrogen peroxide vapor may be easily introduced through the large opening and the vapor easily covers the interior surface of the cup. Furthermore, a hot drying gas may easily flow through and dry the interior of the cup. For containers such as bottles, with an opening to a height ratio of less than 1.0, difficulties arise in attempting to sterilize to aseptic standards the large interior surface. For example, difficulties occur when trying to rapidly introduce a sterilant through the small bottle opening onto the large interior surface. It is difficult to achieve a uniform coating of sterilant over the interior surface. Additionally, the sterilant vapor may condense and form droplets on the surface. These droplets are difficult to remove and can cause residual sterilant levels above an acceptable level. For example, for the sterilant hydrogen peroxide, the residual level must be less than 0.5 PPM in order to meet FDA standards. The small bottle opening also restricts the flow of drying gas that can enter, pass through, and exit the bottle.
Another disadvantage in the design of typical hydrogen peroxide sterilization equipment is the build up of hydrogen peroxide droplets in the delivery nozzles or other delivery apparatus. These droplets can eventually be directed into the container and become impossible to heat and evaporate, and therefore, will result in a residual level of hydrogen peroxide in the container which will be greater than the FDA allowable 0.5 PPM.
Packaged food products can generally be categorized as high acid products (Ph below 4.5) or low acid products (Ph of 4.5 and above). The high acid content of a high acid product helps to reduce bacteria growth in the product, thereby increasing the shelf life of the product. The low acid content of a low acid product, however, necessitates the use of more stringent packaging techniques, and often requires refrigeration of the product at the point of sale.
Several packaging techniques, including extended shelf life (ESL) and aseptic packaging, have been developed to increase the shelf life of low acid products. During ESL packaging, for example, the packaging material is commonly sanitized and filled with a product in a presterilized tunnel under xe2x80x9cultra-cleanxe2x80x9d conditions. By using such ESL packaging techniques, the shelf life of an ESL packaged product is commonly extended from about 10 to 15 days to about 90 days. Aseptic packaging techniques, however, which require that the packaging take place in a sterile environment, using presterilized containers, etc., are capable of providing a packaged product having an even longer shelf life of 150 days or more. In fact, with aseptic packaging, the shelf life limitation is often determined by the quality of the taste of the packaged product, rather than by a limitation caused by bacterial growth.
For the aseptic packaging of food products, an aseptic filler must, for example, use an FDA (Food and Drug Administration) approved sterilant, meet FDA quality control standards, use a sterile tunnel or clean room, and must aseptically treat all packaging material. The food product must also be processed using an xe2x80x9cUltra High Temperaturexe2x80x9d(UHT) pasteurization process to meet FDA aseptic standards. The packaging material must remain in a sterile environment during filling, closure, and sealing operations.
Many attempts have been made, albeit unsuccessfully, to aseptically fill containers, such as bottles or jars having small openings, at a high output processing speed. In addition, previous attempts for aseptically packaging a low acid product in plastic bottles or jars (e.g., formed of polyethylene terepthalate (PET) or high density polyethylene (HDPE)), at a high output processing speed, have also failed. Furthermore, the other fillers have not been successful in providing a high output aseptic filler that complies with the stringent United States FDA standards for labeling a packaged product as xe2x80x9caseptic.xe2x80x9d In the following description of the present invention, the term xe2x80x9casepticxe2x80x9d denotes the United States FDA level of aseptic.
In order to overcome the above deficiencies, the present invention provides an apparatus and method for providing container interior sterilization in an aseptic processing apparatus. The interior container sterilization is applied in an apparatus for providing aseptically processed low acid products in a container having a small opening, such as a glass or plastic bottle or jar, at a high output processing speed. The present invention includes a plurality of sterile air supply sources. For example, a first supply source of sterile air is used to atomize a sterilant (e.g., hydrogen peroxide), within an atomizing venturi. A second supply source of sterile air is used to provide hot sterile air to the atomized sterilant leaving the atomizing venturi. A third supply source of sterile air is used to provide hot sterile air for activating and drying the sterilant on the interior surface of the container. The second supply source of heated sterile air, prevents the formation of hydrogen peroxide droplets. This results in a design that will meet the FDA regulations for each and every bottle that is manufactured. Typically, in the aseptic packaging industry, a low volume of air at a high temperature is applied to the packaging materials. This method works well when the container material can withstand relatively high temperatures such as when cups are made of polypropylene. However, this often results in deformation and softening of packaging materials formed of PET or HDPE. In order to prevent softening and deformation of the bottles, when formed from these types of plastic materials, the present invention applies high volumes of air at relatively low temperatures over an extended period of time in the activation and drying apparatus. A long exposure time is predicated by the geometry of the bottle and the softening temperature of the material used to form the bottle. In the present invention, about 24 seconds are allowed for directing hot sterile air from the third supply source of sterile air into the interior of the bottles. In order to achieve aseptic sterilization, the bottle is maintained at about 131xc2x0 F. for at least 5 seconds. Many features are incorporated into the interior bottle sterilization apparatus in order to meet the various FDA aseptic standards and the 3A Sanitary Standards and Accepted Practices.
The present invention generally provides an apparatus comprising:
a first supply source of sterile air;
a supply source of sterilant;
an atomizing system producing an atomized sterilant from the mixing of the sterile air from the first supply source of sterile air with the sterilant;
a second supply source of a hot sterile air for providing the hot sterile air to the atomized sterilant;
a probe for applying the atomized sterilant into an interior of a container; and
a third supply source of a hot sterile drying air for activating and drying the sterilant in the interior of the container.
Also provided is a method comprising:
providing a first supply of sterile air;
providing a supply of sterilant;
producing an atomized sterilant by mixing the first supply of sterile air with the sterilant;
providing a second supply of hot sterile air to the atomized sterilant;
providing a probe for applying the atomized sterilant into an interior of a container; and
supplying a third supply of hot sterile drying air for activating and drying the sterilant in the interior of the container.